To keep the number of weighing processes per hour as high as possible, a low-pass filter with a relatively low limit frequency cannot be applied to the measurement signal with such weighing devices. Although such low-pass filters would improve the accuracy of the weighing process, and in particular, would allow the accuracy required in the pharmaceutical industry in the first place, the result would not be achievable.
Therefore, rather than use low-pass filters with very low limit frequency in such multiple-track weighing devices, it is commonly known to instead correct the output signal of the force sensor itself of the weighing cell by the detection of disturbing accelerations, and to compensate in this way for the influence of disturbing accelerations.
Such compensation methods are known, for example, from DE 32 30 998 A1 for scales with a single weighing cell. In this weighing device, an acceleration sensor is arranged in the housing of the weighing cell in the immediate vicinity of the moving measurement mechanisms. With this acceleration sensor, substantially the same disturbing accelerations are detected that also act on the load and the mass of the measurement mechanisms. The sensor signal is then amplified to adapt the sensor sensitivity to the sensitivity of the weighing cell, and it is subtracted from the signal of the weighing cell. In this way, a measurement signal is obtained which is corrected by the detected disturbing acceleration, and which ideally depends only on the mass of the load to be weighed. The acceleration sensor is arranged here in such a way that it detects the components of disturbing accelerations that act in the load insertion direction.
From DE 40 01 614 A1 a compensation scale is known in which at least one acceleration sensor is arranged on a mobile part of the scale. The acceleration sensor delivers a signal to an arrangement which processes a correction signal, and which determines at least one correction signal for influencing the measurement result which appears at the output as a measure of weight or of the mass of the load acting on the mobile part. This state of the art also describes the compensation and elimination, respectively, of the influence of translational and rotational disturbing accelerations that act on the base plate of the scale.
However, the use of such weighing cells, with in each case one or more measurement recorders, to construct a multiple-track weighing system would be associated with high costs as a result of the corresponding high number of acceleration sensors.
Therefore, in the construction of multiple-track weighing systems, an appropriate number of weighing cells is arranged on a common base plate, and a single acceleration sensor is arranged on this base plate. The position of the acceleration sensor is chosen here such that it is as characteristic as possible for the disturbing accelerations that can usually be expected, i.e., in such a way that it is possible to use the signal of the single acceleration sensor to correct with sufficient accuracy the measurement signals of the individual weighing cells, which signals have been affected by the disturbing accelerations that have occurred.
However, such multiple-track weighing systems have the disadvantage that in the case where the disturbing accelerations do not affect the individual weighing cells in the same way, a sufficiently exact compensation of the disturbing accelerations is not possible, and in some circumstances an unacceptable error is applied to the generated, corrected weight signals of the individual weighing cells.